Charge coupled devices (CCD's) are semiconductor devices that encode information as quantities of electric charge. Conventional semiconductor devices, in contrast, generally represent information as current levels or voltage levels. This characteristic of CCD's provides them with the benefit of easy transfer of data. As such, an array of closely situated CCD's can readily act as a shift register. Another benefit derived from the use of CCD's is that the charge they store can be sensed non-destructively and hence, the charge can still be used for further applications after being previously sensed.
To date, the use of CCD's in image processing has been quite limited. Current efforts have primarily been limited to exploiting the shifting capability of CCD's or using the CCD's as cameras to convert image data into quantities of electric charge.